Automatic NMC payouts can now be set for for amounts less than 1. It follows the same rules as BTC automatic payouts: Payment thresholds must be multiples of 0.10.
The text on
https://www.btcguild.com/change_auto_payout_nmc.php still says:
Amounts must be multiples of 1 NMC.
Setting to 0.1 works, though.